Make sure collected patches are not mutated.

[eriksunsol]

Extending the example in README.md like this:

var myObj = { firstName:"Joachim", lastName:"Wester", contactDetails: { phoneNumbers: [ { number:"555-123" }] } };
var jsonPatcherProxy = new JSONPatcherProxy( myObj );
var observedObject = jsonPatcherProxy.observe(true);
observedObject.firstName = "Albert";
observedObject.contactDetails.phoneNumbers[0].number = "123";
observedObject.contactDetails.phoneNumbers.push({number:"456"});
observedObject.contactDetails.phoneNumbers[1].number = "789";
var patches = jsonPatcherProxy.generate();

results in the following patch:

[
  {"op":"replace","path":"/firstName","value":"Albert"},
  {"op":"replace","path":"/contactDetails/phoneNumbers/0/number","value":"123"},
  {"op":"add","path":"/contactDetails/phoneNumbers/1","value":{"number":"789"}}
  {"op":"replace","path":"/contactDetails/phoneNumbers/1/number","value":"789"},
]

Note that the last change mutates the already collected patch corresponding to the push operation. The proposed change prevents this by deep-cloning the value placed in the patch so that the result is as expected instead:

[
  {"op":"replace","path":"/firstName","value":"Albert"},
  {"op":"replace","path":"/contactDetails/phoneNumbers/0/number","value":"123"},
  {"op":"add","path":"/contactDetails/phoneNumbers/1","value":{"number":"456"}}
  {"op":"replace","path":"/contactDetails/phoneNumbers/1/number","value":"789"},
]

[warpech]

I am working on adding a test

[warpech]

Thanks for your contribution. This PR continues in https://github.com/Palindrom/JSONPatcherProxy/pull/48